Electric brake

ABSTRACT

A vehicle electric brake with stationary and axially moveable cores providing a V-shape annular recess receiving an endless belt providing a friction liner releasably urged into firm frictional engagement with the cores by an electromagnet mounted in the stationary core. The moveable core is mounted on a wheel hub for rotation therewith and axial movement with respect to the fixed core to engage the belt between the cores and thereby restrain rotation of a wheel on the hub to stop the vehicle.

United States Patent @19 1 Hubbard 1 ELECTRIC BRAKE [75 Inventor: HaroldC. Hubbard, Lansing, Mich.

[731 Assignee: Motor Wheel Corporation, Lansing,

Mich.

[22] Filed: Oct. 1, 1971 [21] App1.No.: 185,664

[52] 11.5. C1 ..l88/l63, 192/84 A, 310/77, 188/7l.4, 188/250 B [51] Int.Cl ..Fl6d 65/34 [58] Field of Search..3l0/77, 93, 103; 188/163, 162,188/161, 164; 192/84 R, 84 A [56] References Cited UNITED STATES PATENTS1,601,791 10/1926 Bing ..l92/84 A 3,268,044 8/1966 Lippman ..192/84 A3,003,609 10/1961 Lang ..188/164 X 3,422,942 1/1969 Spencer ..l88/163 X3,446,322 5/1969 Wrensch 188/163 X Primary Examiner-D. F DugganAttorney-Barnes, Kisselle, Raisch & Choate [57] ABSTRACT A vehicleelectric brake with stationary and axially moveable cores providing aV-shape annular recess receiving an endless belt providing a frictionliner releasably urged into firm frictional engagement with the cores byan electromagnet mounted in the stationary core. The moveable core ismounted on a wheel hub for rotation therewith and axial movement withrespect to the fixed core to engage the belt between the cores andthereby restrain rotation of a wheel on the hub to stop the vehicle.

11 Claims, 1 Drawing Figure This invention relates to vehicle brakingdevices and more particularly to electric brakes suitable for trailersand the like.

Objects of this invention are to provide an electric brake of economicalconstruction and assembly which is substantially maintenance free andhighly effective for braking wheeled vehicles such as boat trailers andthe like.

These and other objects, features, and advantages of this invention willbe apparent from the following description, appended claims, andaccompanying drawing which is a side view partially in vertical centersection of an electric brake embodying this invention mounted on an axleand hub assembly of a vehicle.

The drawing illustrates an electric brake with a stationary core 12 anda rotary and axially moveable core 14 mounted respectively on an axle l6and a wheel hub 18 of a trailer (not shown). An endless circular belt 20with a generally V-shape cross-section is releasably engaged by moveablecore 14 to provide a frictional coupling between the cores which retardsthe rotation of moveable core 14 and associated to hub 18 thusdecelerate or prevent motion of the trailer on which brake 10 ismounted. Belt 20 provides an endless flexible friction ring between thecores which is commercially available from Goodyear Tire and Rubber Co.as catalog No. 8-lR-38U-MP. Stationary core 12 is mounted by a suitablefastener (not shown) in fixed relation to the non-rotary axle housing orother similar structure of the axle assembly (not shown) and if axle 16is a live or rotary axle the same is journaled for free rotation in core12 by a brass bushing 22. If axle 16 is non-rotatable and hub 18 isjournalled thereon by suitable wheel bearings, then core 12 ispreferably welded directly to axle 16. Moveable core 14 is mounted onhub 18 for rotation therewith and for generally axial movement towardand away from stationary core 12 by a plurality of circumferentiallyspaced cylindrical guide pins 23 which slide in complementary,cylindrical pockets 25 in core 14. Pins 23 are pressed into holesthrough bosses 24 on the inner face of a wheel mounting flange 26 of hub18. Bosses 24 are integral with wheel flange 26 and provide positivestops limiting the movement of core 14 away from core 12. Flange 26 isintegral with hub 18 and mounts a wheel and tire assembly (not shown) onthe hub. Guide pins 23 and the associated pockets 25 may have taperingsurfaces in planes radially of the hub converging toward core 12 todevelop a camming action tendency to force core 14 toward core 12 inresponse to restraining torque exerted on core 14 by core 12 via belt20. A servo or self-energizing action is also obtained by the tendencyof belt 20 to be drawn deeper into groove 31 when it is squeezed betweenthe stationary and rotary friction surfaces and 28.

Cores 12 and 14 are made of a magnetic material such as steel or castiron and have a generally cylindrical shape with opposed, inclinedfriction surfaces 28 and 30 providing an annular groove 31 of V-shape orfrusto-conical cross section between their outer peripheral surfaceswhich receives endless belt 20. Belt 20 is retained on stationary core12 by a radial flange 32 having an outside diameter slightly larger thanthe free state inside diameter of belt 20. The bottom of groove 31 isdefined by a cylindrical surface 33 in core 12 extending axially betweensurface 30 and flange 32 and having a diameter preferably .003 inchesless than the free state inside diameter of belt 20. Surface 28 is Iformed on the end of an annular rib 35 of core 14 which axially overlapsand has a radial clearance with flange 52. An electromagnet to move core14 is pro vided by core 12 and a coil 32 of an electrically conductivewire with lead lines 34 received endwise and fixed in an annular groove36 in stationary core 12. Core 14 is moved toward core 12 and intoengagement with belt 20 by an electromagnetic field produced by coil 32acting primarily on a circular rib 38 of core 14 extending with aclearance into groove 36, closely adjacent to coil 32. The wearing awayof endless belt lining 20 by use of brake 10 is automatically adjustedor compensated for by the arrangement of the generally opposed frictionsurfaces 28 and 30 urged into engagement with the belt by theelectromagnet.

Lead lines 34 of coil 32 are connected through suitable controlcircuitry to a source of electrical energy, such as the 12 volt batteryof the towing vehicle. To operate brake l0, coil 32 is energized by thecontrol circuitry which creates a magnetic field attracting core 14axially toward core 12 and urging surfaces 28 and 30 into firmfrictional engagement with endless belt 20, thereby retarding orpreventing rotation of hub 18 and core 14 in relation to stationary core12 and thus braking the vehicle on which the braking device 10 ismounted. The brake is released by de-energizing coil 32 which allowsmoveable core 14 to shift axially away from stationary core 12 anddisengage from endless belt 20. In practice, it has been found that whencoil 32 is de-energized core 14 will remain disengaged or slightlyspaced from belt 20 when core 14 is rotating. However, if desired, core14 can be yieldably biased away from stationary core 12 by anyconvenient means such as a coil spring 40, which is housed in theannular cavity 42 of hub 12 and butted between a radial wall 44 ofcavity 42 and the end surface on annular rib 46 of core 14. A suitablewear ring,48 may be secured to the end turn of spring 40 to slideagainst rib 46. The axially overlap of ribs 35, 38, and 46 of core 14with the concentric annular ribs 50 and 52 of core 12 provides anefficient flux return path for coil 32 which increases the magneticcoupling between the cores, and hence the field strength and concomitantattractive forces, as core 14 moves closer to core 12.

The use of an endless belt of lining material received between frictionsurfaces which can be moved into firm engagement with the belt providesa compact and highly efficient braking device which is of economicalmanufacture and assembly. The endless belt and opposed friction surfacesautomatically compensate for wear of the belt and thus the brake issubstantially maintenance free.

lclaim:

1. A braking device adapted for use in a vehicle having an axle and awheel hub on the axle comprising first and second cores each having afriction surface in generally opposed, spaced relation forming anannular recess having a generally V-shape cross section, an endless beltwith a generally V-shape cross section providing a ring of frictionmaterial received in said annular recess between said opposed surfaces,an electromagnet received in one of said cores and adapted to move saidcores toward each other and said opposed friction surfaces into firmfrictional engagement with said endless belt when. energized, one ofsaid cores being adapted for mounting such that it does not rotate withrespect to the vehicle, the other of said cores being adapted forconnection with the wheel hub for rotation therewith, and one of saidcores also being mounted for generally axial movement toward and awayfrom the other of said cores.

2. The braking device of claim 1 in which said cores are generallycylindrical and one of said cores encircles the axle and the other ofsaid cores is concentric with and mounted on a flange of the wheel hub.

3. The braking device of claim 1 in which said electromagnet comprises acoil of electrically conductive wire encircling the axle and mounted inan annular groove in said one core and in which said other core has anannular rim extending generally axially into said groove adjacent tosaid coil of wire.

4. The braking device of claim 2 in which said electromagnet comprises acoil of electrically conductive wire encircling the axle and mounted inan annular groove in said one core and in which said other core has anannular rim extending generally axially into said groove adjacent tosaid coil of wire.

5. The braking device of claim 1 in which one of said cores has meansretaining said endless belt on said core when at least one of saidopposed friction surfaces is disengaged from said endless belt.

6. The braking device of claim 2 in which one of said cores has meansretaining said endless belt on said core when at least one of saidopposed friction surfaces is disengaged from said endless belt.

7. The braking device of claim 3 in which one of said cores has meansretaining said endless belt on said core when at least one of saidopposed friction surfaces is disengaged from said endless belt.

8. The braking device of claim 7 in which said retaining means of saidone core comprises a generally radially extending circumferential flangespaced from said friction surface of said one core and adapted to retainsaid endless belt on said one core when at lease one of said frictionsurfaces is disengaged from said endless belt.

9. A braking device for a vehicle comprising a wheel hub, first andsecond cores each having a friction surface thereon with the surfaces inopposed spaced relation forming an annular recess with a generallyV-shape cross section, an endless belt with a generally V-shape crosssection providing a ring of friction material received in said annularrecess between said opposed surfaces, one of said cores being concentricwith and carried by said wheel hub for rotation therewith and generallyaxial movement in relation thereto toward and away from the other ofsaid cores, the other of said cores being generally co-axial with saidhub and adapted for mounting in a stationary position with respect tothe vehicle, and an electromagnet received in said one core and adaptedwhen energized to move said cores toward each other and said frictionsurfaces into firm engagement with said endless belt.

10. The braking device of claim 9 in which said one core is adapted tojournal for free rotation an axle d tedf rc ecti tos 'd hub. a Th brgliir ig dt iice o claim 10 further including UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTIGN PATENT NO. 3,734,245

DATED May 22, 1973 INVENTORtS) Harold C. Hubbard It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

The reference numeral "32" where it appears at the top of the singlefigure of the drawings (between reference numerals "20" and "14") shouldbe changed to 52-.

Column 1, line 67 "32" should be 52- Column 2, line 2 "32 should be 52-Signed and Sealed this A ttest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Parentsand Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPATEN'I NO. 1 4,245

DATED May 22, 1973 lNVENTORtS) Harold C. Hubbard It is certified thaterror appears in the ahove-identified patent and that said LettersPatent are hereby corrected as shown below The reference numeral 32"where it appears at the top of the single figure of the drawings(between reference numerals "20" and "14") should be changed to -52-.

Column 1, line 67 "32" should be -52-- Column 2, line 2 "32" should be-52- Signed and Scaled this thirtieth D a): of March 1 976 [SEAL]Attesr:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Parentsand Trademarks

1. A braking device adapted for use in a vehicle having an axle and awheel hub on the axle comprising first and second cores each having afriction surface in generally opposed, spaced relation forming anannular recess having a generally V-shape cross section, an endless beltwith a generally V-shape cross section providing a ring of frictionmaterial received in said annular recess between said opposed surfaces,an electromagnet received in one of said cores and adapted to move saidcores toward each other and said opposed friction surfaces into firmfrictional engagement with said endless belt when energizEd, one of saidcores being adapted for mounting such that it does not rotate withrespect to the vehicle, the other of said cores being adapted forconnection with the wheel hub for rotation therewith, and one of saidcores also being mounted for generally axial movement toward and awayfrom the other of said cores.
 2. The braking device of claim 1 in whichsaid cores are generally cylindrical and one of said cores encircles theaxle and the other of said cores is concentric with and mounted on aflange of the wheel hub.
 3. The braking device of claim 1 in which saidelectromagnet comprises a coil of electrically conductive wireencircling the axle and mounted in an annular groove in said one coreand in which said other core has an annular rim extending generallyaxially into said groove adjacent to said coil of wire.
 4. The brakingdevice of claim 2 in which said electromagnet comprises a coil ofelectrically conductive wire encircling the axle and mounted in anannular groove in said one core and in which said other core has anannular rim extending generally axially into said groove adjacent tosaid coil of wire.
 5. The braking device of claim 1 in which one of saidcores has means retaining said endless belt on said core when at leastone of said opposed friction surfaces is disengaged from said endlessbelt.
 6. The braking device of claim 2 in which one of said cores hasmeans retaining said endless belt on said core when at least one of saidopposed friction surfaces is disengaged from said endless belt.
 7. Thebraking device of claim 3 in which one of said cores has means retainingsaid endless belt on said core when at least one of said opposedfriction surfaces is disengaged from said endless belt.
 8. The brakingdevice of claim 7 in which said retaining means of said one corecomprises a generally radially extending circumferential flange spacedfrom said friction surface of said one core and adapted to retain saidendless belt on said one core when at lease one of said frictionsurfaces is disengaged from said endless belt.
 9. A braking device for avehicle comprising a wheel hub, first and second cores each having afriction surface thereon with the surfaces in opposed spaced relationforming an annular recess with a generally V-shape cross section, anendless belt with a generally V-shape cross section providing a ring offriction material received in said annular recess between said opposedsurfaces, one of said cores being concentric with and carried by saidwheel hub for rotation therewith and generally axial movement inrelation thereto toward and away from the other of said cores, the otherof said cores being generally co-axial with said hub and adapted formounting in a stationary position with respect to the vehicle, and anelectromagnet received in said one core and adapted when energized tomove said cores toward each other and said friction surfaces into firmengagement with said endless belt.
 10. The braking device of claim 9 inwhich said one core is adapted to journal for free rotation an axleadapted for connection to said hub.
 11. The braking device of claim 10further including an axle connected to said hub and journaled for freerotation in said one core.